Abstract

Objectives: To explore the driving problems associated with Parkinson’s disease (PD) and to ascertain whether any clinical features or tests predict driver safety.

Methods: The driving ability of 154 individuals with PD referred to a driving assessment centre was determined by a combination of clinical tests, reaction times on a test rig and an in-car driving test.

Results: The majority of cases (104, 66%) were able to continue driving although 46 individuals required an automatic transmission and 10 others needed car modifications. Ability to drive was predicted by physical disease severity, age, presence of other associated medical conditions particularly dementia, duration of disease, brake reaction time on a test rig and score on a driving test (all p<0.0001). Level of drug treatment and length of driving history were not correlated. Discriminant analysis revealed the most important features in distinguishing safety to drive were severe physical disease (Hoehn & Yahr stage 3), reaction time, moderate disease associated with another medical condition and high score on car testing.

Conclusions: Most individuals with PD are safe to drive although many benefit from car modifications or using an automatic transmission. A combination of clinical tests and in-car driving assessment will establish safety to drive and a number of clinical correlates can be shown to predict likely outcome and may assist in the decision process. This is the largest series of consecutive patients seen at a driving assessment centre reported to date and the first to devise a scoring system for on- road driving assessment.